Narrative:

Air carrier X en route on J94 over eck. Captain and I noticed lack of radio chatter. Captain asked toronto center if they heard our radio. Toronto responded with, 'I just sat down--who and where are you?' we advised, 'air carrier X, over fnt, 350.' toronto advised we should be with ZOB. About this time we noticed air carrier Y above us on jet route. We called ZOB on assigned frequency. ZOB responded with a request to state position and altitude. Apparently air carrier Y had been given clearance to descend through our altitude, but saw us and stopped 2000' above and passed by (same direction). At this point I looked at the transponder switches and noticed that switch #1 or 2 was in the off position. This has happened many, many times on this model medium large transport. Also toronto had failed to make a 'hard' handoff to ZOB. ZOB saw our primary return, but it was under the other aircraft's encoded display. Also on arrival into den the transponder switch went to the off position one more time with nothing in proximity to the switch which could make it move. I think the situation over fnt was caused by a combination of: 1) toronto failing to hand our flight off to zlb, and 2) our flying into ZOB's airspace with the transponder in the off position. Transponder switches are slowly being replaced on our fleet--too slowly!! Supplemental information from acn 141669: when we noticed that we hadn't heard toronto for some time, we requested a radio check and were informed that there had been a shift change and we were given a ZOB frequency. Upon contacting ZOB, were informed that they had a primary target but no transponder, so requested a transponder code. We switched xponders and squawked requested code. ZOB then had radar contact. Apparently ZOB had no idea we were coming into their airspace and gave air carrier Y a descent clearance through our altitude. Air carrier Y made visibility contact with us and returned to his last altitude. He then overtook and passed 2000' above.

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Original NASA ASRS Text

Title: ACR X ENTERED ZOB AIRSPACE WITHOUT RADAR HANDOFF OR COORD. OPDEV.

Narrative: ACR X ENRTE ON J94 OVER ECK. CAPT AND I NOTICED LACK OF RADIO CHATTER. CAPT ASKED TORONTO CENTER IF THEY HEARD OUR RADIO. TORONTO RESPONDED WITH, 'I JUST SAT DOWN--WHO AND WHERE ARE YOU?' WE ADVISED, 'ACR X, OVER FNT, 350.' TORONTO ADVISED WE SHOULD BE WITH ZOB. ABOUT THIS TIME WE NOTICED ACR Y ABOVE US ON JET RTE. WE CALLED ZOB ON ASSIGNED FREQ. ZOB RESPONDED WITH A REQUEST TO STATE POS AND ALT. APPARENTLY ACR Y HAD BEEN GIVEN CLRNC TO DSND THROUGH OUR ALT, BUT SAW US AND STOPPED 2000' ABOVE AND PASSED BY (SAME DIRECTION). AT THIS POINT I LOOKED AT THE XPONDER SWITCHES AND NOTICED THAT SWITCH #1 OR 2 WAS IN THE OFF POS. THIS HAS HAPPENED MANY, MANY TIMES ON THIS MODEL MLG. ALSO TORONTO HAD FAILED TO MAKE A 'HARD' HDOF TO ZOB. ZOB SAW OUR PRIMARY RETURN, BUT IT WAS UNDER THE OTHER ACFT'S ENCODED DISPLAY. ALSO ON ARR INTO DEN THE XPONDER SWITCH WENT TO THE OFF POS ONE MORE TIME WITH NOTHING IN PROX TO THE SWITCH WHICH COULD MAKE IT MOVE. I THINK THE SITUATION OVER FNT WAS CAUSED BY A COMBINATION OF: 1) TORONTO FAILING TO HAND OUR FLT OFF TO ZLB, AND 2) OUR FLYING INTO ZOB'S AIRSPACE WITH THE XPONDER IN THE OFF POS. XPONDER SWITCHES ARE SLOWLY BEING REPLACED ON OUR FLEET--TOO SLOWLY!! SUPPLEMENTAL INFO FROM ACN 141669: WHEN WE NOTICED THAT WE HADN'T HEARD TORONTO FOR SOME TIME, WE REQUESTED A RADIO CHK AND WERE INFORMED THAT THERE HAD BEEN A SHIFT CHANGE AND WE WERE GIVEN A ZOB FREQ. UPON CONTACTING ZOB, WERE INFORMED THAT THEY HAD A PRIMARY TARGET BUT NO XPONDER, SO REQUESTED A XPONDER CODE. WE SWITCHED XPONDERS AND SQUAWKED REQUESTED CODE. ZOB THEN HAD RADAR CONTACT. APPARENTLY ZOB HAD NO IDEA WE WERE COMING INTO THEIR AIRSPACE AND GAVE ACR Y A DSNT CLRNC THROUGH OUR ALT. ACR Y MADE VIS CONTACT WITH US AND RETURNED TO HIS LAST ALT. HE THEN OVERTOOK AND PASSED 2000' ABOVE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.